/* function fn(x: string): void
function fn() {

}
fn('hello') */

/* function fn(x: boolean): void
function fn(x: string): void
function fn(x: boolean | string) {

} */

function fn(x: string): string
function fn(x: boolean): boolean
function fn(x: string | boolean): string | boolean {
  // return 'hello'
  return true
}